1. Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Yongin 17104, Republic of Korea
2. Integrated Education Institute for Frontier Science & Technology (BK21 Four), Kyung Hee University, Yongin 17104, Republic of Korea
3. Flash Process Development Team, Samsung Electronics, 1, Samsungjeonja-ro, Hwaseong-si, Gyeonggi-do 18448, Republic of Korea